Regex patterns with concatenated raw strings are inferred as Pattern[LiteralString] instead of Pattern[str] #2129

Describe the Bug

After upgrading from 0.48.0 to 0.48.1, I now see a warning with code like this:

import re

pattern = re.compile(r'hi' + r'hi')
re.match(pattern, '')  # No matching overload found for function `re.match` called with arguments: (Pattern[LiteralString], Literal['']) [no-matching-overload]

Pyright, ty, mypy, and zuban infer the pattern variable as Pattern[str] instead of Pattern[LiteralString].

Version info

ab249da

Sandbox Link

https://pyrefly.org/sandbox/?project=N4IgZglgNgpgziAXKOBDAdgEwEYHsAeAdAA4CeSIEAtsbgE4AuABHTADrofGoMMx3omAXhYxCAY1w1oMABR0A5AAsICpgGoWy1QEoOrQlR7ils7r37oANEwUK96EFZABXBtDglyiEAGImAKruUBAMpExgLuji7rjocBwcmDBgEfRGDAD66C5U2Pyy%2BIhMEOgMOkwAtAB8THAMdIgcTC2iDC4CEWwgAHK5%2BY1MwPgAvt0cTiBkrGBQpIQMUlAU-gAKpDNzdRg4BEyS6JAA5h08EHGEHP4AyjAwTEq8xHCIAPSv0ylzhPRHrzDoV6YXDiOCvA7HU6xQFpOhMVAAN1Q0FQ2Fg%2BzikLoZziTFwxGhni4pAYSjilQR-Dg50EIm6AGZCABGABM40cI2cqBiEEpADEZBQ0Fg8EQyCARkA

(Only applicable for extension issues) IDE Information

No response